Two often competing concerns in today's society are security and convenience.
People are increasingly looking to ways of increasing security—for example in terms of securing physical possessions.
At the same time, however, people are increasingly looking for convenience. As a generalisation, people do not generally want to carry additional bulky items, despite the fact that such items can increase security.
Electronic devices can be used to increase security, but in order to counter the general aversion of people have to carrying additional items, such devices must be small. Small devices, however, carry small batteries which either drain quickly and/or require relatively frequent recharging—both of which compromise the convenience to end users.